Green Chemistry Homework problem answers:
1. Find the structure of at least three of the POPs given in Table 13-2. What is the common
structural feature in these compounds? Are any or all of them legal to use currently in the
US? Cite the source for your information—please NEVER use Wikipedia.
Aldrin
Dieldrin
DDT
Cl
Cl
Cl
CCl3
Cl
Cl
O
Cl
Endrin
Chlordane
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Heptachlor
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
O
Hexachlorobenzene
Toxaphene
Mirex
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
These compounds share a heavily chlorinated structure, most often containing bicyclic or
polycyclic structures (or aromatic rings)
DDT—banned in US in 1973-- http://www2.epa.gov/aboutepa/ddt-ban-takes-effect
Aldrin—banned in US--http://www.popstoolkit.com/about/chemical/aldrin.aspx;
http://scorecard.goodguide.com/chemical-groups/one-list.tcl?short_list_name=brpest
Dieldrin—most uses banned in 1987--http://www.epa.gov/pbt/pubs/aldrin.htm
Endrin—most uses banned in 1980-http://water.epa.gov/drink/contaminants/basicinformation/endrin.cfm
Chlordane—Banned in 1983 (except for termites)-http://nlquery.epa.gov/epasearch/epasearch?querytext=chlordane&fld=ttnatw01&area
name=Technology+Transfer+Network+Air+Toxics+Web+Site&areacontacts=http%3
A%2F%2Fwww.epa.gov%2Fttn%2Fatw%2Fcontact.html&areasearchurl=&result_te
mplate=epafiles_default.xsl&filter=sample4filt.hts
Heptachlor—insecticide banned in all food products in 1978, banned from seed treatment
in 1983-http://nlquery.epa.gov/epasearch/epasearch?querytext=Heptachlor&fld=ttnatw01&are
aname=Technology+Transfer+Network+Air+Toxics+Web+Site&areacontacts=http%
3A%2F%2Fwww.epa.gov%2Fttn%2Fatw%2Fcontact.html&areasearchurl=&result_t
emplate=epafiles_default.xsl&filter=sample4filt.hts
Hexachlorobenzene—banned as a pesticide in 1984-http://www.toxipedia.org/display/toxipedia/Hexachlorobenzene;
http://pmep.cce.cornell.edu/profiles/extoxnet/haloxyfopmethylparathion/hexachlorobenzene-ext.html
Mirex—banned in 1978--http://www.epa.gov/pbt/pubs/mirex.htm
Toxaphene Banned since 1990-- http://www.epa.gov/ttnatw01/hlthef/toxaphen.html
There are many good websites for data, but I like the EPA site, since they are most
involved in regulation therefore most up to date and reputable (?)
2. Everything is toxic; it is all a question of dosage. Find the LD50 values for the following
compounds around the house: Bleach, gasoline, acetaminophen, capsaicin (from hot
peppers!) and Windex. Calculate how much Windex you would need to ingest to reach
the LD50 dosage. You may assume the Windex has the same density as water. Please
convert this value into cups, to give yourself a good visualization.
Bleach: LD50 (oral mouse) 5800 mg/kg
Gasoline: LD50 (oral rat) 18.75 mL/kg ~ 13,000 mg/kg
Acetaminophen: LD50 (oral rat) 1900 mg/kg
Capsaicin: LD50 (oral mouse) 47.2 mg/kg
Windex: LD50 (oral mouse) 5000 mg/kg
Estimate 150 lb person:
150 lb * ( 1 kg/ 2.2 lb) * (5 g Windex / kg) * (0.996 g / mL) * (1 cup / 236.59 mL)
= 1.44 cups
3. Why would Harpin (a pesticide, section 2.16) not be expected to accumulate in the
environment in the same way that many other pesticides do?
Harpin is a bacterial protein, and is normally found in many plant cells (not a non-native
compound). The wastes from the synthesis of this compound are biodegradable. Being a
natural product it is highly sensitive to degradation, it is rapidly decomposed by
microorganisms in the soil, and by UV light from the sun, therefore it will not accumulate
in water or biomass
4. a) The first dry cleaning solvents were gasoline and kerosene. What are the hazards
associated with these solvents? b) PERC replaced these chemicals as a popular solvent in
the middle of the 20th century. What are the hazards associated with PERC? What
advantage did it have over kerosene? c) Liquid CO2 is now a popular replacement
solvent for PERC. Does this new solvent have any associated hazards?
a) Gasoline and kerosene—both are highly flammable liquids with high vapor pressures;
gasoline is a suspected carcinogen and both are associated with neurotoxic effects from
long term exposures. b) PERC is not flammable, but tends to accumulate in the fat
tissues. Short term exposure can cause nervous system problems, long term exposure can
cause memory loss and confusion, liver and kidney damage, and cancer. As a gas, PERC
can contribute to photochemical smog (but it tends to react quickly before reaching the
upper atmosphere so it is not thought to damage the ozone layer). c) One of the biggest
hazards of liquid CO2 is the fact that it must be kept under pressure, therefore poses and
explosion hazard. Large volumes released suddenly will displace air; therefore can be
deadly via suffocation. It is often kept cold, which can lead to dangers of freezing
damage to skin
5.
Even though most ions have extremely high melting points, ionic liquids melt near room
temperature. What are the features in ionic liquids which lead to this low mp? What are
the advantages to using an ionic liquid in place of a typical organic as a solvent?
Ionic liquids usually utilize at least one ion (generally the cation) which is a large organic
species where the charge is dispersed over a region (usually a resonating charge). The
large size and diffusion of charge means that the cations and anions are poorly
coordinated. Since they cannot form tight ion pairs, these systems usually have low
melting points
Ionic liquids are not flammable, and they have extremely low vapor pressures (so little
explosion hazard or VOC release). They are good at dissolving a variety of organic,
inorganic, and polymeric materials, so less solvent can be used to dissolve things. They
have a wide liquid range so can be used for high-temperature reactions, yet they resist
oxidation like other organics would do at high temps.
6. Find an old reaction from lab—you may use your own data or find a current organic lab
student and bribe them to share data with you. List the reagents, solvents, catalyst,
products/byproducts for the reaction being performed. Calculate a theoretical yield for
the reaction. Calculate atom economy for this reaction.
Many answers possible. Should utilize reagents consumed (not catalysts or solvents).
For the most part, high theoretical yields in classical syntheses will still have low atom
economies.